User Authentication

VERIFY PIN

This command is used to authenticate the user by verifying their PIN. A successful verification authenticates the session until the card is deselected, reset, or a signature command is performed.

def verify_pin(pin: str)
	card.verify_pin(pin)

For example, verify_pin("123456789")

Application Protocol Data Unit (APDU) Components

The following table outlines the components of the Application Protocol Data Unit (APDU).

Field	Description	Value
CLA	This field specifies the class of the instruction.	0x80
INS	This field specifies the particular command or operation that the smart card or secure element should execute.	0x20
P1	First parameter of the instruction that specifies the details about the operation being requested.	0x00
P2	First parameter of the instruction that specifies additional details about the operation being requested.	0x00
Data	PIN data (optional)	None, or the PIN (4–9 digits, zero-padded to 9)

📘 Note

A Secure Channel must be established before issuing this command.
Two modes of operation:

Without data: Returns the number of remaining PIN retries (1 byte).
With data: Verifies the PIN.

PIN length must be 4–9 digits, zero-padded to 9 bytes if shorter.
On success: The PIN is marked authenticated until the card is reset/power-cycled, the application is deselected, or a signature command is executed.
On error: The retry counter decreases and the card returns 0x63Cx.
On error: When retries reach 3 remaining, a power cycle is required before further attempts.
On error: When retries reach 0, the PIN is blocked.

Input Validation Rules

PIN:

Must be 4–9 numeric digits.
If fewer than 9 digits, pad with 0x00 until 9 bytes total.

No data case: Command simply queries the retry counter.

Response

The following table outlines the possible responses that you will receive:

Response Code	Description
0x9000	PIN verified successfully. PIN is now authenticated for the session. The retry counter is reset.
0x63Cx	Wrong PIN. x = remaining retries.
0x63C0	No retries left in this power cycle (PIN locked until reset). Even the correct PIN returns this code. If persists after the power cycle → PIN is blocked, must use UNBLOCK PIN.
0x6700	Incorrect data length (PIN not 4–9 digits or padding error).
0x6986	Card not initialized, no PIN provided, or PIN authentication disabled (via SetPinAuth).